An integrated circuit (IC) die is often fabricated into a microelectronic device such as a microprocessor. The increasing power consumption of microprocessors results in tighter thermal constraints for a thermal solution design when the microprocessor is employed in the field. If the transistors of the integrated circuit get too hot they can be damaged. Accordingly, a thermal interface is often needed to allow the integrated circuit to release heat more efficiently. A thermal interface can include such things as a heat sink or fan.
Various techniques have been employed to transfer heat away from a die. These techniques include passive and active configurations. One passive configuration involves a conductive material in thermal contact with the backside of a packaged die. This conductive material is often a slug, a heat spreader, or an integrated heat spreader (IHS).
A heat spreader is employed to spread and dissipate the heat generated by a die, which minimizes concentrated high-heat locations within the die. A heat spreader is attached proximately to the back side of a microelectronic die with a thermally conductive material, such as a thermal interface material (TIM). A TIM can include, for example, thermally conductive gels, thermal greases, or solders. Heat spreaders include materials such as aluminum, copper, copper alloy, or ceramic, among others.
With conventional technology, a packaged microelectronic device includes a die which is bonded from the back side to an integrated heat spreader (IHS). An IHS adhesive layer acts as a TIM to bond the die to the IHS. The conventional IHS includes a lip portion that is formed by a bending process which gives rise to less than complete filling into the corner of the bend. Additionally to form the lip portion of the IHS from a rectangular blank, several stamping processes are required to deliver sufficiently flat upper and lower surfaces to achieve quality bonds with other structures such as heat sinks and dies, respectively. These stamping processes result in a relatively low yield in the production of heat spreaders, due, at least in part, to the processes used for forming heat spreaders. Additionally, the stamping processes result in a significant variation in flatness of the top surface of the IHS, as well as the bottom surface. The surface flatness can detrimentally affect adhesion to either side of the IHS.
The current IHS, typically manufactured from a high purity copper alloy, is difficult to form with existing stamping equipment limitations, especially with respect to maintaining high raw material yield metrics and fully-filled corner geometries that are achieved with the stamping process. In order to completely fill the corner locations of the IHS, typical industry raw material yields range as low as 35%, yet utilize multi-stage manufacturing with high-tonnage machinery. The surface flatness is a large contributor to the fall-out and yield problems. Thus far the manufacture of finished packages with heat spreaders has been expensive and time consuming.
Thus, a need still remains for a wafer scale heat slug system that can deliver good thermal performance, package integrity and can use existing assembly tools. In view of the ever increasing performance and shrinking space for integrated circuits, it is increasingly critical that answers be found to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.